<template>
  <section class="todoapp">
    <!-- header -->
    <header class="header">
      <input 
        class="new-todo" 
        autocomplete="off" 
        placeholder="Todo List" 
        @keyup.enter="addTodo">
    </header>
    <!-- main section -->
    <section 
      v-show="todos.length" 
      class="main">
      <input 
        id="toggle-all" 
        :checked="allChecked" 
        class="toggle-all" 
        type="checkbox" 
        @change="toggleAll({ done: !allChecked })">
      <label for="toggle-all"/>
      <ul class="todo-list">
        <todo
          v-for="(todo, index) in filteredTodos"
          :key="index"
          :todo="todo"
          @toggleTodo="toggleTodo"
          @editTodo="editTodo"
          @deleteTodo="deleteTodo"/>
      </ul>
    </section>
    <!-- footer -->
    <footer 
      v-show="todos.length" 
      class="footer">
      <span class="todo-count">
        <strong>{{ remaining }}</strong>
        {{ remaining | pluralize('item') }} left
      </span>
      <ul class="filters">
        <li 
          v-for="(val, key) in filters" 
          :key="key">
          <a 
            :class="{ selected: visibility === key }" 
            @click.prevent="visibility = key">{{ key | capitalize }}</a>
        </li>
      </ul>
      <!-- <button class="clear-completed" v-show="todos.length > remaining" @click="clearCompleted">
        Clear completed
      </button> -->
    </footer>
  </section>
</template>

<script>
import Todo from './Todo.vue';

const STORAGE_KEY = 'todos';
const filters = {
    all: todos => todos,
    active: todos => todos.filter(todo => !todo.done),
    completed: todos => todos.filter(todo => todo.done)
};
const defalutList = [
    { text: 'star this repository', done: false },
    { text: 'fork this repository', done: false },
    { text: 'follow author', done: false },
    { text: 'vue-element-admin', done: true },
    { text: 'vue', done: true },
    { text: 'element-ui', done: true },
    { text: 'axios', done: true },
    { text: 'webpack', done: true }
];
export default {
    components: { Todo },
    filters: {
        pluralize: (n, w) => n === 1 ? w : w + 's',
        capitalize: s => s.charAt(0).toUpperCase() + s.slice(1)
    },
    data() {
        return {
            visibility: 'all',
            filters,
            // todos: JSON.parse(window.localStorage.getItem(STORAGE_KEY)) || defalutList
            todos: defalutList
        };
    },
    computed: {
        allChecked() {
            return this.todos.every(todo => todo.done);
        },
        filteredTodos() {
            return filters[this.visibility](this.todos);
        },
        remaining() {
            return this.todos.filter(todo => !todo.done).length;
        }
    },
    methods: {
        setLocalStorage() {
            window.localStorage.setItem(STORAGE_KEY, JSON.stringify(this.todos));
        },
        addTodo(e) {
            const text = e.target.value;
            if (text.trim()) {
                this.todos.push({
                    text,
                    done: false
                });
                this.setLocalStorage();
            }
            e.target.value = '';
        },
        toggleTodo(val) {
            val.done = !val.done;
            this.setLocalStorage();
        },
        deleteTodo(todo) {
            this.todos.splice(this.todos.indexOf(todo), 1);
            this.setLocalStorage();
        },
        editTodo({ todo, value }) {
            todo.text = value;
            this.setLocalStorage();
        },
        clearCompleted() {
            this.todos = this.todos.filter(todo => !todo.done);
            this.setLocalStorage();
        },
        toggleAll({ done }) {
            this.todos.forEach(todo => {
                todo.done = done;
                this.setLocalStorage();
            });
        }
    }
};
</script>

<style lang="scss">
  @import './index.scss';
</style>
